The present invention relates to cleaning devices and methods, in particular devices and methods for cleaning the interior cavities of contaminated surgical and diagnostic instruments.
The invention has been developed primarily for use in cleaning endoscopes and will be described hereinafter to reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.
An endoscope is an elongate cylindrical instrument that may be rigid or flexible and which incorporates an optical, or video, system and a light source. The endoscope is configured such that one end can be inserted to some depth into a surgical incision or body cavity so surfaces at or near the internally inserted end of the endoscope can be viewed by an external observer.
For example, at present, the longest commonly used endoscope is a flexible endoscope called a colonoscope. A colonoscope is used for diagnostic and surgical procedures of the human colon. The colon insertion portion of the instrument is approximately 2 metres long and has one or more hollow channels, or lumens. These lumens are typically 2-4 mm in diameter and run the length of the endoscope. They allow for gas to be injected into the colon to inflate the organ or enable liquids to be sucked out. Additionally, long flexible instruments can be inserted down these or other lumens to allow biopsies to be taken and the wound to be cauterised. These biopsy samples are then drawn back through the lumen and sent for pathology testing.
New endoscopes can achieve exceptional results in performing a variety of surgical procedures whereby very small (2 cm) incisions are all that is required, rather than the previous procedures which required incisions of over 20 cm in length. Furthermore, endoscopic procedures usually enable patients to leave hospital after two or three days rather than the previously necessary 7 to 10 days. Overall, trauma is dramatically reduced.
However, a problem inherent with endoscopes is the contamination of the lumen with biological material from the patient, for example, mucous, saliva, faeces, blood, pieces of tissue etc.
While endoscopes have developed greatly in recent times, most, of the developments have concentrated on technical aspects such as the use of optical fibres and lenses, electronic controls and other engineering features. Progress in the cleaning and disinfection of endoscopes has largely not kept pace with the engineering and electronics developments. More recently very sophisticated chemical and biochemical products have been developed, for example, multi-enzyme detergents which digest all human secretions which may be on endoscope surfaces in order to pre-clean instruments before they are disinfected. Also relatively recently new sterilising-systems using hydrogen peroxide plasma or peracetic acid at elevated temperature have become available.
All soiled endoscopes require thorough and efficient cleaning (known as xe2x80x9cpre cleaningxe2x80x9d) prior to disinfection or sterilisation. Disinfection or sterilisation of an instrument which has not been completely cleaned is impossible and leads to patient infections.
The current procedure for cleaning an endoscope entails the following steps.
1. Removal of the soiled endoscope from the patient.
2. Rinsing the soiled instrument in a sink with a copious amount of water and wiping down the outer sheath with a single use paper or non-woven fabric wipe.
3. Rinsing the endoscope lumens with water using a large syringe or other water jet.
4. Brushing the lumens with an endoscope cleaning brush whilst the instrument is immersed in water.
5. Digestion of the contaminants by immersing the instrument in a multi-enzyme detergent bath. In some places detergent is used rather than enzymes.
6. Rinsing the instrument and the hollow channels with water and then air blowing to substantially dry the surfaces in order to avoid dilution of disinfectants.
The endoscope is then ready for disinfection or sterilisation.
In some variations of the procedure, step 4 and 5 are replaced by a step of brushing while the endoscope is immersed in an enzyme detergent bath.
Typically, the endoscope cleaning brush referred to above has a long flexible stainless steel body composed of a flexible stainless steel wire core covered by tightly coiled flexible stainless-steel. The diameter of this body section is approximately 1 mm. At the end of the body is a 30 mm section of nylon bristles. These flexible bristles are usually interwoven with the stainless steel coils. The bristle section is approximately 5 to 6 mm in diameter. The cleaning brush is used to briskly brush backwards and forward along the whole length of the lumen of the endoscope to remove the maximum amount of biological matter contamination prior to enzyme digestion.
Typically, cleaning brushes used for endoscope cleaning receive a clean and disinfection between each cycle of use, in that they are given a water rinse soaked in an enzyme bath, and usually receive the same disinfection as the endoscope itself. There are no limits on the number of cycles of use of such cleaning brushes and many remain in use after most or at least a significant number of bristles have broken away.
Some procedures, for example diagnostic examination of the human oesophagus and stomach can be accomplished in 10-15 minutes after the patient is sedated, while cleaning and disinfecting, would require over 30 minutes.
Endoscopes are expensive instruments, many costing up to between $20,000-$50,000. Because of this high price, practitioners tend to purchase only the minimum number of instruments necessary to ensure a smooth work flow. As a result, there is considerable pressure to disinfect the endoscope for only the shortest effective time. Any improvement in the time required to disinfect the endoscopes has the potential to reduce the number of instruments which a practitioner needs to purchase.
It is an object of the present invention to provide a device and method to improve the speed and/or efficiency of cleaning endoscopes and the like.
According to a first aspect the invention consists in apparatus for use in cleaning a contaminated lumen of an endoscope, said apparatus comprising a wiping member adapted to pass axially through the lumen with at most a small clearance, whereby contamination, if any, remaining after passage of the member through the lumen is substantially uniformly distributed about the interior of the lumen as a thin film.
For preference the wiping member is attachable, or more preferably permanently attached to an elongate shaft or cable. This may be flexible for flexible endoscopes or rigid for rigid endoscopes. The member may include wiping elements which are, for example, a disk disposed orthogonally to the shaft or it may be a cylinder, sphere, cone, spiral or the like. It is preferred to use one or more disk-shaped fins as wiping elements as these provide a more effective scraping action.
Wiping members which are not fully circumferential at their trailing member leave ridges of contaminant when pulled through the endoscope. The number of ridges will depend upon the design. Even if a number of partially circumferential segments occlude one another to present a full circumference when viewed end on, the trailing member will leave ridges in the contaminant film where the edge of the partially circumferential segment is drawn through the contaminant.
In a particularly preferred embodiment, the wiping member includes approximately 50 circular segments of similar size in close proximity and disposed at 90xc2x0 to the shaft.
According to a second aspect the invention consists in a method for cleaning a contaminated lumen of an endoscope comprising the steps of:
Pulling or pushing a wiping member axially through the lumen, the wiping member being adapted to wipe the internal wall of the lumen or to pass through with a small clearance whereby remaining contaminants, if any, after passage of the member are uniformly distributed about the interior wall of the lumen as a thin film; and treating the uniform film with a cleaning composition.
In the use of the method, the cleaning composition preferably includes one or more enzymes.
Experiments have been conducted by the present inventor using a transparent tube of the same diameter as an endoscope lumen contaminated with compositions similar to those encountered in use and using the prior art cleaning method. This has revealed that the nature of the bristles mainly serve to move the viscous liquid with its suspended particular matter backwards and forwards rather than to remove it from the hollow tube. The thick viscous, non flowing biological material is simply redispersed in an uneven fashion throughout the lumen, creating in places thick deposits or xe2x80x9cridgesxe2x80x9d of biological materials that may not be fully digested by the enzymes in the short period of the cleaning phase or are digested more slowly than thinner film sections in the xe2x80x9cvalleysxe2x80x9d between ridges.
The resulting uneven distribution of the contamination increases the overall cleaning time. The thickness of the deposits is a rate determining factor in the enzyme digestion step.
The inventor has found that by use of the present method a much greater proportion of contaminant can be removed in a single pass through the lumen and any remaining contaminant is spread much more uniformly and as a thin film which is rapidly and uniformly attacked during the digestion step.
According to a third aspect the invention consists in a method for manufacture of an endoscope cleaning apparatus comprising the step of moulding a wiping member comprising one or more radially directed fins in situ on an elongated shaft or cable.
The wiping member may be formed integrally with the shaft, or may be made separately. It may have a solid core or a hollow core.